Polymer–clay nanocomposites: Free-radical grafting of polyacrylamide onto organophilic montmorillonite

• Published in: European polymer journal 2010-09, Vol.46 (9), p.1844-1853
• Main Authors: Mansoori, Y., Atghia, S.V., Zamanloo, M.R., Imanzadeh, Gh, Sirousazar, M.
• Format: Article
• Language: English
• Subjects: Applied sciences; Clay (material); Cloisite 20A; Composites; Exact sciences and technology; Forms of application and semi-finished materials; Grafting; Hydroxyl groups; Montmorillonite; Nanocomposites; Nanostructure; Organophilic clay; Polyacrylamide; Polyacrylamides; Polymer industry, paints, wood; Polymerization; Sodium; Technology of polymers
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2010.07.006

This paper is an account of the experiments on grafting polyacrylamide onto organophilic montmorillonite. Cloisite 20A was reacted with vinyltrichlorosilane to replace the edge hydroxyl groups of the clay with a vinyl moiety. Since the reaction liberates HCl, it was performed in the presence of sodium hydrogencarbonate to prevent the exchange of quaternary alkyl ammonium cations with H + ions. Only the silanol groups on the edge of the clay react with vinyltrichlorosilane. The product maintained the same basal spacing as the precursor. The radical polymerization of the product with acrylamide as a vinyl monomer leads to chemical grafting of polyacrylamide onto montmorillonite surface. The homopolymer formed during polymerization was Soxhelt extracted from the grafted organoclay. Chemical grafting of the polymer onto Cloisite 20A was confirmed by IR spectroscopy. The interlayer and surface changes of the clay in the prepared nanocomposite materials and the grafted nano-particles were studied by XRD and SEM. Intercalated nanocomposites were obtained for clay contents of 3–7% and agglomeration occurred at higher clay loadings. The nanocomposites were studied by thermogravimertic analysis (TGA) and dynamic mechanical analysis (DMTA).